The opening of the eyes of our understanding and spiritual knowledge of the truth of God's Word is absolutely necessary for deliverance from the spirit of deception.
Without the opening of the eyes of our spiritual understanding, freedom is impossible. Satan can actually overcome us and bring us into bondage even when we believe God by faith if we do not exert action in the spiritual realm. When you have discerned the deception of the enemy and recognized the conversations of the enemy within the mind and wills of the flesh (that of physical impulse), you will begin to gain ground on the enemy of your soul.
Deception unlatches the gate for evil spirits to come in; passivity provides a place for them to stay. This combination of deception and passivity equals entrenchment of the soul (mind, will, emotions). The common factor for entrenchment is the inactivity of your own God-given free will.
We as Christians in our ignorance have been deceived by the powers of the darkness and have fulfilled the conditions for the enemy to work in our lives.